Control Fluorescent Lights with a Laser Pointer and an Arduino

Step 2 Wiring the lights

Have a look in the ceiling and decide where you will mount the Arduino controller.  Remember that it will need a 7-12v poweer supply. Cut lengths of telephone wire (or cat5 or whatever) about two feet longer than the distance from the Arduino to each light you want to control.

Have a look at the connection from the power lines from the switch into the ballast.  You might be able to order connectors (Newark Electronics sells the Wago 930 series, which is what we had).  Then you won't need to cut existing wires and can remove the system if something goes wrong.

Solder the ground (black) to the relay input -, and the control (yellow) to relay input + (the color code in the picture is different from what I put on the front page, since I changed my mind about what would make sense).

Solder or screw on (depending on your relay) the black (hot) wire through the relay.  Make sure to use heat shrink and electrical tape!  Push the black wires into your connectors and the white (neutral) and ground (green) are just straight through from connector to connector.

The other end of the wires go to the Arduino as follows:
All the red wires (common cathode or collector) go to Analog 0 (port C0), and all the black to ground.  Each green (anode or emitter) goes to pins 8-13 (port B 0-5) and the yellow wires go to the pins 2-7 (port D 2-7).  Make sure that the green and yellow wires match up, since the sensor needs to control the proper relay!  If you put the yellow into pin 2, the green from the same fixture goes to pin 8.